A great deal of evidence suggests that visual perception is affected by our predictions about the visual world. Prediction allows us to exploit and adapt to the causal, non-random structure of our visual environment, and is essential for rapid and accurate control of visually guided behavior. We previously identified neuronal signals in the monkey lateral intraparietal area (LIP) that provide a predictive representation of the direction of visual motion. The overarching issues in this new proposal are the relationship of predictive signals to behavior and the mechanisms by which predictive signals develop. Predictive motion signals in LIP seem ideally suited for feedforward control of behavior, but little is known about the relationship between predictive neuronal signals and behavior. We will address this issue by looking for trial-by-trial correlation between predictive neuronal signals and reaction time. We will examine 1 both manual reactions and eye movements to test whether the activity of single neurons is specific for particular behaviors, or rather provides a general predictive signal that is useful for multiple behaviors. We will also examine whether predictive neuronal signals and behavioral advantages arise as a result of learning based on the recent trial history of visual stimulation. We specifically hypothesize that predictive neuronal signals are updated based on prediction errors, the difference between the predicted visual stimulus and the actual visual stimulus. Moreover, we hypothesize that predictive behaviors and predictive neuronal firing will be similarly affected by recent trial history. Finally, another "extraretinal" process, selective attention, has been shown to enhance sensorimotor behaviors and to modulate neuronal responses. A key question is whether the dynamics of the neuronal modulation can account for the behavioral advantage. We will simultaneously examine the time course of neuronal modulation and the time course of the performance advantage that is gained when an animal endogenously switches attention between two visual stimuli in response to a cognitive cue. The time course of attentional modulation of a neuronal response should reflect the role that a neuron plays in endogenous shifts of attention. Our experiments will provide a mechanistic perspective on how the brain uses prior information about the sensory world to facilitate perception and action. Gaining basic information on perceptual mechanisms is an essential step for understanding normal and abnormal brain processing.